Origin of trigger-angle dependence of di-hadron correlations.

Abstract

The STAR Collaboration reported measurements of di-hadron azimuthal correlations in medium-central Au+Au collisions at 200A GeV, where the data are presented as a function of the trigger particle’s azimuthal angle relative to the event plane φs . In particular, it is observed that the away-side correlation evolves from a singleto a double-peak structure with increasing φs . In this work, we present the calculated correlations as functions of both φs and the particle transverse momentum pT , using the hydrodynamic code NeXSPheRIO. The results are found to be in reasonable agreement with the STAR data. We further argue that the above φs dependence of the correlation structure can be understood in terms of the one-tube model, as due to an interplay between the background elliptic flow caused by the initial state global geometry and the flow produced by fluctuations.